Printing telegraph



H. L. FAULDiNG PRINTING TELEGRAPH Filed April 6, 1932 2 Sheets-Sheet l INVENTOR HLS ATTORNEY May 3, H. L. PAULDING l 35 PRINTING TELEGRAPH Filed April 6, 1952 2 Sheets-Sheet 2 BC} M '23 m I 1 24 HIS ATTORNEY Patented May 1,1934

UNITED STATES PATENT: OFFICE PRINTING TELEGRAPH Application April 6, 1932, Serial No. 603,468

'28 Claims.

This invention relates to printing telegraph systems, and more particularly to systems in which a succession of electrical pulses, of predetermined magnitude and direction, are sent from a central transmitting station through transmission lines, to one or more receiving, or subscribers, stations where these pulses actuate a printing mechanism which prints the messages in a column of convenient width, as distinguished.

from the printing of messages in a single line upon a continuous linear carrier, or tape. The present apparatus is sometimes referred to as a page printer or ticker to distinguish it from the socalled tape printer.

These systems are used most frequently for the dissemination of the latest news simultaneously to subscribers who may be located at widely separated points and consequently it is important that the messages be sent and transcribed in the shortest possible time. Because of the greater flexibility afforded, and for other reasons, it has been found expedient to operate the transmitting apparatus manually. However, this arrangement has not imposed a speed limitation upon these systems because the rate of reproducing a message has been controlled by the speed of the receiving, or printing, apparatus, which have heretofore operated at speeds considerably slower than the average operator can transmit. One of the features of this invention is the construction and arrangement of the receiving, or printing, mechanism, together with the associated electrical circuits, in such manner that the messages may be reproduced at the subscribers stations at r speeds much higher than has been possible heretofore.

In the operation of such systems it has been found desirable to lease the transmission wires from others rather than maintain separate lines for the exclusive use of these systems. Frequently, wires in cables which carry telephone lines have been leased andsince they reach practlcally every subscriber, this arrangement has proved satisfactory. However, unless precautions are taken, the pulsing of currents in the telegraph lines may cause objectionable noises to arise in the telephone lines, by reason of the capacity and inductive pick ups existing between these two lines. the former coupling being dependent upon changes in voltage and the latter coupling dependent upon current changes. In the past it was customary to transmit over the lines the current necessary to operate the printing apparatus and to vary this current from a positive value to the corresponding negative value.

This resulted in comparatively large swings of current and voltage which gave rise to noises in the telephone lines.

Another feature of this invention, therefore, is to minimize these disturbances by transmitting over the telegraph lines current pulses considerably lower in magnitude than used in the old systems and which go from zero to a positive value and return for all operations of the printing mechanism except during the sending of a repeat pulse when a current of negative polarity is transmitted. Thus the variations in currents and in voltages transmitted over the lines are reduced considerably and accordingly decrease the pick up in the telephone lines with the result that fewer disturbances from these causes are now found in these lines. The currents now transmitted over the lines, under the present system, are maintained below the comparatively large values necessary to operate the receiving apparatus and are used to actuate relays which control local sources of power used to operate the apparatus.

It is desirable that the ticker, or printingapparatus, may be started and stopped under the control of the transmitter and without requiring the subscriber to do anything. Another object of this invention is to provide means whereby the subscribers ticker may be started up by sendingv the usual pulses from the transmitter, and stopped automatically by sending over the line a long negative pulse, or, in another arrangement, after the transmission of pulses has been discontinned for a convenient time, say several minutes.

Of course, if the subscriber should wish to stop the apparatus he may disconnect it from the local source of power. Since the machine may function in normalfashion without any attention on the part of the subscriber, it is convenient to provide means, operable by the'transmitter, for calling the subscribers attention to important news items; thus in the present system, a bell is provided. k

In printing telegraphs of the type to which this invention relates, it is customary to employ a type wheel, with the printable characters thereon, which is rotated intermittently in one direction under the control of aselection-escapement oscillated by a so-called unison magnet which, in turn, is controlled by the pulses coming over the line. The paper upon which the message is to be printed is pressed against the printing wheel by the movement of an armature associated with a. so-called press magnet. This armature is associated with a printing-escapement mechanism. 110

It will be understood that with such an arrangement the unison magnet must be adapted to oscillate the selection-escapement at high frequencies corresponding to the selecting, or pulsing 'frequencyofthe apparatus, while the press magnet armature is actuated at substantially lower frequencies. a

As pulsing and printing pulses alternately follow each, other in rapid succession during operation of the device, it is necessary that the apparatus be sufliciently selective to distinguish between the frequencies of these two types of pulses so that the pulses of the higher frequency will actuate the selection-escapement mechanism and the pulses of the lower frequency will actuate the printing-escapement mechanism without interference with each other. further object of this invention is to provide suitable apparatus and circuit arrangements for these mechanisms which possess the requisite s lectivity and which are simple in construction and efiicient in operation. The means here dis closed not only accomplish these results but also cooperate with other apparatus to control the operation of the subscribers motor which actuates the various ticker mechanisms.

Another object of this invention is to design the circuit containing the unison and press magnets in such a way that the current which isobtained from the local source of supply may be used to actuate both magnets thereby avoiding the complicity of providing separate circuits and additional apparatus for the two distinct operations controlled by these magnets. This object is accomplished, as will be described more fully hereinafter, by inserting a condenser in the circuit of the press magnet and tuning that circuit to the pulsing frequency.

A further object is to provide a rectifier circuit to adapt the apparatus for use with alternating current. Additional features of the invention will be apparent, and the invention will be better understood, from the following description and the accompanying drawings, in which,

Fig. 1 is a diagrammatical representation of certain parts of the transmitting and receiving apparatus, showing an electric circuit arrangement which includes a rectifier and a mechanically operated motor switch;

Fig. 2 is a somewhat simplified wiring diagram of a preferred electric circuit arrangement containing thermal switches for the motor and for ringing a bell, a direct current source of power being available;

Fig. 3a illustrates the form of pulses transmitted in a system heretofore widely used, showing alternate reversals of current from positive to negative polarities; and

Fig. 3b illustrates the form of pulses transmitted according to the present invention, the current varying from zero to a positive value except in repeating when the direction of current flow is reversed. F

Transmitter-A brief reference to the transmitter will be made to explain how it operates to transmit pulses which vary in the manner shown in Fig. 3 (b), instead of in the usual way illustrated in Fig. 3 (a). In Fig. l a pin cylinder 1 is mounted upon a shaft 2 which is connected to a motor through a slip clutch (neither the motor nor the clutch are shown) so that this cylinder may be rotated continuously or it may be stopped at will without stopping the motor. At one end of the pin cylinder is a commutator 3 comprising a number of electrically conduc- Therefore, a still tive portions, or segments 4, and an equal number of insulating segments 5, arranged in an alternate series as illustrated. The total number of segments is the same as the number of characters which it is desirable to provide for the machine, for example, thirty-eight. A disc 6 is conductively connected to each of the segments 4. Brushes '7 and 8 contact with the commutator 3 and the disc 6, respectively, so that as the commutator rotates, the circuit across these two brushes will be closed each time the brush 7 comes in contact with a conductive segment 4 and will be opened again whenever this brush contacts with an insulating segment, 5. The number of segments which pass the brush 7, after a character has been printed at the ticker, determines the number of pulses which are sent over the l ne to select the next letter to be printed. The sending of the required number of pulses is controlled by the pin cylinder 1 and the keys 9 which are pivoted upon a rod 10. A series of projections or pins 11, also corresponding in number to the characters to be printed, are located upon the pin cylinder in. a helical arrangement, as illustrated. When a key 3 is depressed the rear end 12 of this key is raised so that it lies in the path of one of the pins 11 which, when it contacts with the end 12, prevents the pin cylinder from rotating further and a long, or printing pulse is sent over the line. When another key is pressed down, the first key is raised by suitable means (not shown) and the pin cylinder is again rotated until the pin 11 which lies in alignment with the second key, contacts with this key, and the pin cylinder is stopped again.

The selection of a character to be printed is accomplished through the transmission or" a certain number of positive pulses over the line by means of the following circuit arrangement. The circuit of the brushes 7 and 8, starting from the former, include the wire 13, a direct current generator 18 which constitutes the source of the line currents, a pulsing relay l6 and the wire 17 connected to the brush 8. The generatoralso supplies current to an independent repeat circuit including the following: generator 18, repeat key 14 and repeat relay 15. The armatures of the two relays, normally urged to the left by the springs, as illustrated, are connected to the line 21. The left hand contact points 22 and 23 of these relays are connected by the wire 24 to the point 25 on one side of the generator and the right hand contacts 26 and 2'? of these relays are connected by the wire 28 to the point 29 on the other side of the generator.

-When the circuit across the brushes 7 and 8 is closed during selecting and printing, the current pulses flowing through the line 21 are traced as follows: Current flows from the generator 18 to the point 29 where it divides, part of it flowing through the pulsing relay 16, energizing it to move the armature to the right, thence through the wire 17, across the brushes '7 and 8, through the wire 13 to the other terminal 19 of the generator; the other part of this current flows from point 20 to point 29, thence to the contact point 26 of the pulsing relay, through the armature and out over one side of the line 21; returning from the ticker in the other side of the line, the

current flows through the armature of the repeat relay 15 to the contact point 23 and thence through the wire 24 to the point 25 from which it returns to the terminal 19 on the other side of the generator 18. This is called a positive pulse.

When it is desired to end a repeat pulse, or negative current over tlie'line, the operator closes the repeat key 14. It is now necessary to avoid energizing the pulsing relay 16 in order that its armature may remain to the left in engagement with contact point 22. This is accomplished by using the repeat action only to repeat a space on the ticker for which the transmitter is so arranged that during this time the circuit is broken across the brushes '7 and 8. It is possible to repeat one half of the total number of characters, that is, all those which are printed when the brush 7 contacts with an insulating segment 5 on the commutator so that no current is flowing in the line. However, in actual practice, it was found convenient to repeat spaces only. When this negative pulse is sent over the line the circuit is traced as follows: Current flows from the generator terminal 20 to the point 29 Where it divides, part of it flows through the repeat relay 15, thus energizing it to move the armature so that it touches contact 27, through the repeat key 14 and back to the terminal 19 of the generator; the other part or the current flows from point 29 through the wire 28 to contact point 27, thence through the repeat relay armature and over one side of the line 21; returning by the other side of the line, the current flows through the armature of the pulsing relay 16 to the contact point "22, thence through the wire 24 to the point 25 and the terminal 19 of the generator.

The pulses are sent from the transmitting apparatus to each subscribers receiver, or ticker, over the line 21, which may consist of certain wires leased in a cable carrying telephone, or other wires, as referred to above. It has already been pointed .out that the flow of impulses through these leased wires may be the cause of objectionable noises in the telephone wires because of the capacity and inductive pick up existing between these wires. that in the operation of the old system of transmitting impulses, as represented in Fig. 3a, the currents flowing through these leased wires varied from 200 milliamperes in one direction to the same value in the other direction, a net change of 400 milliamperes. Likewise, the voltage varied between 120 volts positive and 120 volts negative, a swing of 240 volts. Under the present system of operation the current varies between a maximum value of 30 milliamperes at 120 volts positive, and zero, for all operations except for repeat and bell ringing in which instance it assumes a value of 30 milliamperes at 120 volts negative. Since capacity and inductive pick up vary in accordance with changes in voltage and current, respectively, in a direct relation, it will be appreciated that the reduction of each of these pick ups, as described above, results in less distortion in the telephone lines.

The various operations which take place at the receiver in the reproduction of a message are under the control of two relays which are connected across the line 21 in series and through each of which the transmitted pulses flow. These relays are made selective to pulses of different polarities and hence each causes diii'erent operations to be performed at the receiver according to whether the line current is flowing in one direction or the other. Relay 30 is known as the pulsing relay. Being polarized it is actuated only when positive impulses are sent over the line 21 for the purpose of selecting the next character to be printed, and for subsequently printing that It will be appreciated character. Relay 31, the repeat relay, controls the repeating of characters, and is also polarized, being actuated by negative pulses only. The pulsing relay 30 comprises the armature 32, the upper contact point 33 and the lower contact point 34; repeat relay 31 has an armature 35 and contact points 36 and 37. The armatures of these two relays are connected through the wire '38 and, as represented in the drawings, each armature is normally held against one contact by means of a spring.

Assume that a short positive pulse is sent over the line 21. By reason of the selectivity of pulsing relay 30, the armature 32 thereof will be moved away from the contact 33, breaking the circuit through the armature at that point, and brought to the contact 34 where the circuit through the armature will be transferred. If this pulse be of short duration only, then the armature will remain only a short time against the contact 34 after which the armature spring will force it into engagement with the contact point 33. As will be apparent from the description which follows, these comparatively short pulses are used to control the oscillation of the selection-escapement for the purpose of selecting the next character to be printed. During the printing operation, the positive pulses sent over the line 21 are much longer in duration and the armature of the pulsing relay contacts for a correspondingly longer time with the contact point 34. It will be noted that while the pulsing relay is able to distinguish between positive and negai tive pulses, moving only on the former, it is not selective as between pulses of long or short duration, that is, its armature moves whether the apparatus is printing or pulsing. The selection between these two operations of the receiver is accomplished by means of the novel arrangement of the circuit of the press magnet, to be described later.

Now assume that it is desirable to repeat a space. The space just printed left the line opened so that the armature 32 of the pulsing relay 30 is against contact 33 and will remain there. now a negative-pulse is sent over the line 21, the armature 35 of the repeat relay, heretofore inactive, will be pulled from contact 36 to 37. The efiect of this change as will be described, is to maintain the selection-escapement in a fixed position while permitting the press escapement to be actuated in order to print that space again. From the pulsing relay contact 33 a wire 39 is .connected to a point 40 on one of the leads to the motor 41 which is preferably ahdirect current motor with shunt fields 42. The othei'relay contact 34 is connected by the wire 43 to the termihal- 44 of a motor cut out switch 45 which is connected by the wire e7 to the point 48 on the other lead to the motor 41. The motor switchis a single polo, double throw switch having associated with it another terminal 46 which is connected by the wire 49 to the contact point 36 of the repeat relay. A spring connected to the switch, as shown, normally urges it toward the terminal 44 so that the circuit through the motor 41 tends to remain closed. This switch is opened by means of the following mechanism controlled the press magnet which is described hereinafter.

which. when the armature is pulled down by the magnet, strikes a lug 52 on the member 53. The upper end of this member is provided with a projection 54 which normally rides in a helical groove The armature 50 of this magnet is prorid-3d at its left hand end with a projection 51 If so ISJ nected at one end to the worm follower 53 and when this follower is drawn to the left by the rotation of the worm 55 the other end of the rod '56 is'forced against the switch 45 and-causes it to break the circuit through terminal 44 and to establish it through terminal 46. This" condition will continue as long as the worm follower net and its associated escapement. is accomplished by tuning" the press magnet by 53 remains in engagement with the worm 55, that is, until the armature of the-press magnet is pulled down. When this occurs the worm follower is withdrawn from the worm and a spring 57 pulls the follower and the rod '56 away from the motor switch 45 which then comes into contact again with terminal 44. The worm is so designed with respect to its speed of rotation that it takes about one minute for the motor switch to throw over in the manner described. Thus the circuit through the motor remains closed while the press armature is up for short intervals such as occur in the ordinary operation of the ticker.

Tracing through the circuitshown in Fig. 1 it will be observed that the press magnet and the unison magnet are in series between the pulsing relay 30 and the motor 41. Thus a wire 58 connects the armature 32 of this pulsing relay to thepress magnet, a wire 59 connects this press magnet to the unison magnet, and another wire 60 connects the latter to a point 61 located midway between the motor fields 42.

Press magnet circzdL-Referring to the circuit diagram of Fig. 1, and the description above, it will be understood that the circuit through the press magnet is closed when either selecting or printing pulses are coming vover the line 21 and since the pulsing relay armature 32 moves in the same direction in both cases, it is necessary to provide some means whereby the press magnet is actuated only by-the printing pulses, permitting the selecting pulses topass on to the unison mag- Briefly, this means of a condenser, acting in conjunction with the inductance of the magnet coils, in such a way that its armature is moved only by printing pulses; selecting pulses flowing through this magnet without causing the armature to move. Assume, for example, that the selecting pulses are transmitted at a frequency of 60 cycles per second and the printing pulses are transmitted at 20 cycles. There is then available a comparatively wide difference between these frequencies so that the tuning of the press magnet need not be very i sharp to function properly.

Referring now to the circuit of the press magnet as shown in Fig. 1 it will be observed that there are four windings upon the core of this magnet, the two upper windings 62 and63 being in series and the two lower windings 64 and 65 likewise being inseries. The upper windings lie in one'branch of a parallel circuit between the junction points 66 and 67, while the lower windings lie in the other branch of that circuit. All of the coils have the same number of turns so as to set up the same magnetic flux for the same current, but it should be noted that the upper and'lower coils on either side of the core are reversed in direction of winding so that normally j the flux set up in these coils oppose each other.

, Thus it will be understood that when the same currents flow through the upper and lower series of coils in this parallel circuit arrangement, the resultant flux of the magnet is substantially zero and the armature 50 thereof, held away by a printing pulses.

spring (not shown) will not be attracted. This is the condition which exists when the ticker is receiving selection pulses. If now, the branch containing the coils 62 and 63 be opened, only the flux of the coils 64 and 65 in the other branch would be set up and since there would be no opposing flux set up by the coils 62 and 63 the magnet would be energized to attract the armature 50. This occurs when the ticker is receiving The necessary opening and closing of the one parallel branch is attained by means of a condenser 68 inserted in this branch.

The capacity of this condenser isso selected with,

respect to the inductances of the press magnet" coils that at the pulsing frequency say 69 cycles per second, the impedance of this condenser is low enough to permit the selecting pulses to flow equally through both branches of the press magnet while at the printing frequency, the impedance of this condenser becomes'infinite and breaks the circuit through the upper parallel branch.

In order to avoid the necessity for providing means to furnish currents of, different magnitudes to the press magnet and to the unison magnet which are in series with each other, it is desirable that these magnets should operate on the same current, that is, the pulsing and the printing currents of the ticker should be of substantially the same value. As the frequency increases from the printing value to that of pulsing, the impedance of the unison magnet increases proportionately to decrease the current but this decrease is compensated by reason of the parallel circuits of the press magnet in the following manner. With this magnet tuned by the condenser to the pulsing frequency it becomes a unity power factor circuit so that current flows through both branches and the impedance of this parallel arrangement becomes approximately one-half of its direct current resistance. Thus by selecting a condenser of the proper value with respect to the inductances in the circuit of the magnets, the increased impedance of the unison magnet may be substantially balanced by the decreased impedance of the press magnet.

It is necessary during the pulsing operation, as pointed out above, that the currents in the capacity and inductive branches of the press magnet be substantially equal. But it is known, of course, that the currents flowing in each of these branches will not vary in exact accordance with the variations in the pulsing current, nor will they vary in the same manner in each branch. Currents in the one branch will vary more or less in accordance with the flow of current through a condenser subjected to varying voltages and current though the other branch will follow the flow of current through an inductance. The currents in the two branches, therefore, will ordinarily be out of phase and hence unequal and the magnetic flux of the magnet unequal. If however, suitable resistances 69 and 70 be added in each branch, the variation of current flow in each branch may be so modified that the currents flowing in each are substantially equal at all times. The total current flowingthrough the press magnet is, of course, equal to the sum of the currents in these separate branches. While the introduction of these resistances broadens the tuning of the press magnet, it offers no real difficulty in distinguishing between selecting and printing pulses because of the comparatively great difierence between the frequencies of these two operations.

Printing mechanism-As has been previously explained, a character is printed when a long, or printing pulse is sent over the line from the transmitter, and causes the armature of the press magnet to be attracted. Referring to Fig. l, the printing wheel '71 upon which the characters are located is mountedupon a print shaft '72 which is connected by a slip clutch (not shown) to the motor 41 so that the printing wheel tends to rotate continuously. However, as explained later, it is held stationary during the printing cycle. A platen 73 is positioned in back of the printing wheel as shown and is adapted to push the paper 74 against this wheel to print the various characters. This platen is hinged upon the rod '75 and is provided with an arm '76 which extends below a cam I'Tupon the cam shaft '78. This shaft has mounted on it an escape wheel '79 adapted to be engaged by the pallets of escapement anchor 80 and this shaft is also, connected by a slip clutch to the motor 41 so that it tends to rotate continuously in the direction of the arrow. This anchor is connected by a shaft 81 to an arm 82 which is connected to the armature of the press magnet. When the armature 50 is attracted the anchor 80 disengages the escape wheel 79 by permitting this shaft to rotate and cause the projections 83 on the cam '77 to force the platen arm '76 downward, thus causing the platen to push the paper against the character to be printed.

Unison magnet and escapement.--The selection of the characters to be printed by the ticker is under the control of the unison magnet and the escapement associated therewith. Briefly, the escapement anchor oscillates, during selectmg or pulsing, a certain number of times depending upon the relative position of the character to be printed with respect to the one last printed, and during printing, the escapement is held stationary to hold the printing wheel at the character to be printed. The print shaft 72 upon which the printing wheel 71 is mounted, tends to rotate continuously under a constant torque from the motor 41, as previously explained. Upon the end of the print shaft is mounted the toothed escape wheel 84 with which the escapement pallets 86 engage. This wheel has onehalf as many teeth as there are characters on the printing wheel; for example, if there are thirty-eight characters there will be nineteen teeth on this wheel. While a character to be printed by the ticker is being selected by means of the pulses coming over the line 21 the escapement anchor 85 oscillates in step with these pulses so that the pallets 86, are alternately inserted into and withdrawn from, the teeth on the escape wheel. The print shaft, and the printing wheel, thus rotate under the torque of the motor 41 as long as the escapement anchor oscillates in thisway. After the necessary number of pulses has come over the line 21, permitting the printing wheel '71 to rotate to the selected character, the line condition of the last selecting pulse (either a positive current or no current) is continued for a printing period to actuate the printing mechanism; the cscapement 85 remaining stationary and holding the printing wheel in position while the character is being printed.

As illustrated, the escapement anchor 85 has a depending portion 87 which acts as the armature of the unison escapement magnet. This is a polarized magnet comprising a permanent magnet 88 and the coil 89 wound around its armature. As represented, the armature is pivoted at point 90 between the pole pieces 91 and it will be understood that the armature (and the escapement anchor) will be drawn toward these pole pieces alternately according to the direction of current flowing through the armature coil 89.

Rcctifier.-It has been'found desirable to use a direct current motor 41 and consequently where there is only alternating current available as the local source of supply it is necessary to convert this to direct current for use in the ticker. A preferred arrangement of a rectifier is illustrated in Fig. 1. It comprises an auto-transformer 92 to which the line 93 of the alternating current supply is connected at the lower end as indicated at 94. The other side 95 of the supply is connected to the mid point 96 of the transformer through the motor cut-out switch 45. The lower half of the coil 92, between the points 96 and 94 thus comprise the primary of the transformer. The ends of the secondary (the whole coil) are connected to the plates of a rectifier tube 9'7. The filament of this tube is heated by a low voltage secondary 98 coupled with the coil 92. The output leads 99 and 100 of the rectifier are connected respectively from the mid-point of the filament coil 98 to the point 40 on the lead to the motor 41, and from the mid point 96 of the auto-transformer 92 to the point 48 on the other lead to the motor. A filter comprising the choke coils 101 and condensers 102 is preferably associated with the output leads from the rectifier.

Stopping.The ticker stops automatically on the transmission of a long negative signal of several minutes duration; the length of time depending upon the design of the worm associated with the cut-out switch 45. The signal coming over the line puts the armature 35 of the repeat relay 31, in contact/with 37 as shown in Fig. 1, closing the circuit through press coils 62 and 63. The armature 59 of this magnet remains de-energized so that the worm 55 forces the rod 56 associated with the worm follower 53 to open the motor switch 45. Thus the current supply to the motor 41 is broken; tracing the circuit from the line 95 of the supply, it will be observed that the circuit is broken at the terminal 44 of the motor switch and also at the contact point 34 of the pulsing relay. When stopped, the machine is left with the cut out switch armature 45 in contact with 46 and relay armatures 32 and 35 on contacts 33 and 36, respectively.

Starting.-As long as the armature of the press magnet remains de-energized the motor cut-out switch 45 will remain on terminal 46 and the motor 41 will remain at rest. But if a positive signal long enough to cause the rectifier to deliver direct current, be sent over the line 21 to the ticker, the motor will start. Such a signal pulls the armature 32 of the pulsing relay against the contact 34. The starting circuit istraced as follows: from the supply through the wires 95 and 43 to the contact point 34 of the pulsing relay, thence through the armature 32 of this relay, the wire 38 and the armature 35 of the repeat relay to the contact point 36, through the wire 49 to the terminal 46 of the motor cut-out switch 45, through the wires 47 and 100 to the mid-point of the transformer 92, thence through the lower half of the transformer to point 94 and from there through terminal 44 and so establishing normal running conditions.

Unison.If for some reason the printing wheel 71 should not print the character which is trans- -mitted over the line 21 but instead prints some can be started again in unison.

To bring the various tickers into unison in this way the operator at the transmitter holds down a unison key which has no corresponding stop pin on the pin cylinder 1 and therefore the commutator 3 and the disc 6 turn freely thus sending a comparatively long series of selecting pulses over the line 21. The escapement anchor 85 is thereby caused to oscillate in step with these pulses, permitting the print shaft 72 to rotate as long'as the unison key is held down at the transmitter. It will be'observed that a wormv 103 is mounted upon the print shaft 72 and that the end of a follower rod 104 is adapted to engage in this worm. The other end of this follower rests upon the upper surface of the print wheel shifting rack 105 which, when moving back and forth as in normal printing operation, lifts the end of the follower 104 out of the worm 103. When this occurs a spiral spring wound about the follower, as shown, forces the upper end of the follower to move to the left hand end of the worm 103. But during this unison operation the feed rack 105 remains stationary so that the follower remains in engagement with the worm and the print shaft continues to rotate until the follower catches in 'the'unison latch 107 on the worm. It is found desirable to arrange the apparatus so that this occurs when the printing wheel has stopped at a "space. The operator, after holding the unison key down long enough to insure that all the machines have thus stopped, prints a space. Thereafter when normal operation is commenced all the tickers start off with the printing wheels .in unison with the transmitter.

Repeat action.-As previously pointed out in the description of the transmitter, the repeat action can be actuated only when the line is free to permit a negative current to be sent over it. When the repeat key 14 at the transmitter is closed under this condition the repeat relay 31 is energized and its armature contacts with point 37 which is connected by a wire 108 to a point 109 on one of the branches of the press magnet circuit. The condenser 68 in this branch is thus short circuited so that the currents in thetwo branches of the press magnet are equal causing the armature thereof to be released, and ready to operate the printing mechanism again. When the repeat key is opened the condenser is not short circuited and the press magnet again actuates the printing escapement and the character is reprinted. Since the pulsing relay 30 was not energized by the repeat (negative) pulse the selection escapement has held the print shaft 72 stationary and the printing wheel 71 remains stationary to reprint the character as often as desired. In practice it has been found advantageous to repeat the space character only.

For the purpose of testing the apparatus it may be desirable to insert a line testing jack 110 in series with the line 21 as shown and to insert a jack 111 for testing the pulsing and repeat relays.

Referring to Fig. 2, in which the same reference numerals have been applied to designate the same parts, there is shown a. slightly modified circuit arrangement connected to a direct current source of power and embodying thermally controlled switches for the motor 41 and for ringing a bell to attract attention to important news items. In this circuit the motor is started by a positive signal over line 21, which energizes the pulsing relay, and thus closes a heater circuit in the motor cut out switch. This switch comprises a bi-metallic member 112, the ends of which are confined between two points nearer to each other than the normal length of this member so that it assumes a double flexure as shown by the full lines in Fig. 2. Adjacent to this member are two heater resistances 113 and 114, the former being of about 500ohms and the latter about 5000 ohms. These resistances are in series between the points 115 and 116 and to their junction point 117 the terminal 118 of the switch is connected. The other terminal 119 of the switch is connected to the pulsing relay contact 34. The normal, or unheated, position of the switch 112 is against the terminal 118. The starting circuit is traced as follows: Beginning with the wire 120 of the local supply, current flows to the pulsing relay contact 34 against which the armature has been pulled by the positive pulse, through the armature to point 115 and thence through the resistance 113 to terminal 118, through the switch 112, across the motor 41 and through the wire 121 to the supply. The passage of current through the resistance 113 generates sufficient heat to act upon the bimetallic member 112 to force it to change its position 'so that it springs over to contact with the terminal 119 as represented by the dotted lines. Current then flows directly from the wire 120 to theswitoh 112 and across the motor as before. Since the terminal 118 no longer contacts with the switch, current flows through both resistances, 113 and 114, but as this current is limited by these resistances to a comparatively small value, its heating effect upon the switch is arranged to be just sufficient to keep the switch against the terminal 119. As the transmission of current pulses stops for a predetermined time the switch cools 01? and springs into contact with the terminal 118 thus breaking the circuit at terminal 119 and stopping the motor.

7 Another thermal switch 122 is employed in the circuit of the bell 123 which is connected across the motor leads as shown at points 124'and 125.

The bi-metallic member of this switch is heated by a resistance .126 connected between the repeat relay contact 37 and a point 127 on one branch of the press magnet circuit. When the repeat relay is energized by a long negative pulse, as

distinct from short negative repeat pulses, enough heat is generated in resistance 126 to snap the switch 122 against its terminal 128 thus closing the bell circuit and causing the bell to ring. On releasing the repeat key the circuit is again opened allowing the switch to resume it normal position on cooling.

I claim:

1. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of one polarity, also to transmit space repeating, current pulses of the opposite polarity and receiving apparatus comprising a plurality of circuit elements each of which is responsive to currents of a single polarity, a printing mechanism associated with said elements and actuated by said printing pulses only, and character-selecting mechanism actuated by said selecting pulses.

2. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of one polarity, also to transmit space repeating current pulses of the opposite polarity, receiving apparatus comprising circuit controlling elements each of which is actuated by currents of one polarity only, printing and selecting mechanisms associated with said elements, whereby these elements control the operations of character selecting and printing, and space repeating, in accordance with the pulses received.

3. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of one polarity, also to transmit space repeating current pulses of the opposite polarity, receiving apparatus comprising a circuit controlling element actuated by pulses of the selecting and printing polarity only, a second circuit controlling element actuated by pulses of thespace repeating polarity only and printing and selecting mechanisms associated with said elements, said printing mechanism being actuated by printing pulses only whereby the receiving apparatus selects and prints characters and repeats spaces in accordance with the pulses received.

4. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting current pulses of a single polarity and receiving apparatus comprising a pulsing relay and a selecting mechanism associated therewith, said relay being energized by currents of the selecting polarity only and when so energized closing the associated circuit of said mechanism so that currents therein flow in one direction, and when deenergized currents flow in the opposite direction whereby the selecting mechanism is actuated in accordance with the selecting pulses received.

5. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of a single polarity and receiving apparatus comprising a pulsing relay and printing and selecting mechanisms associated therewith, said relay being energized by currents of the selecting and printing polarity only and when so energized closing the associated circuits of said mechanisms so that currents therein flow in one direction, and when deenergized currents flow in the opposite direction, said current reversals occurring at the selecting frequency and said printing mechanism being actuated by the printing pulses only, whereby the selecting and printing of characters is accomplished in accordance with the pulses received.

6. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of a single polarity and receiving apparatuscomprising a selecting mechanism, and a printing mechanism, a circuit arrangement for actuating said printing mechanism and containing a capacity adapted to permit the flow of selecting pulses but to blockprinting pulses whereby said printing mechanism is actuated by printing pulses only and said selecting mechanism is actuated by the selecting pulses.

'7. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of a single polarity and receiving apparatus comprising a selecting mechanism, and a printing mechanism, a circuit arrangement for actuating said printing mechanism including a magnet having a plurality of energizing coils in parallel branches, a capacity in one of said branches adapted to permit the ow of selecting pulses but to block printing pulses in said branches whereby said printing mechanism is actuated by printing pulses only and said selecting mechanism is actuated by the selecting pulses.

8. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of a single polarity and receiving apparatus comprising a selecting mechanism, and a printing mechanism, a circuit arrangement for actuating said printing mechanism including a magnet having a plurality of energizing coils in parallel branches, the coils in. each branch being so wound that the magnetic flux developed by the coils of one branch are opposed by the coils'of the other branch, a capacity in one of said branches adapted to permit the magnet which when energized actuates said mechanism, a circuit arrangement for energizing said magnet, said circuit including a capacity to make said circuit resonant to some pulses only.

10. In a printing telegraph system, apparatus adapted to transmit pulses of the same polarity but of different frequencies and receiving apparatus comprising a printing mechanism, an electro-magnet which, when energized actuates said mechanism, a circuit arrangement for energizing said magnet including a plurality of coils in parallel branches, the successive coils in each branch being wound in opposite directions, and means for opening the circuit of one parallel branch during the flow of pulses of some frequencies to energize said magnet whereby said printing mechanism is actuated by certain pulses only.

11. In a printing telegraph system, apparatus adapted to transmit pulses of the same polarity but of different frequencies and receiving apparatus comprising a printing mechanism, an electro-mag'net which, when energized actuates said mechanism, a circuit arrangement for energizing said magnet during the flow of pulses of one frequency and for preventing the energizing of said magnet duringthe fiow of pulses of another frequency whereby said printing mechanism is actuated by pulses of the first frequency only.

12; In a printing telegraph system, apparatus adapted to transmit pulses of the same polarity but of different frequencies and receiving apparatus comprising a printing mechanism, an elec-- tro-magnet for actuating said mechanism, a circuit arrangement for energizing said magnet including a plurality of coils in parallel branches, the successive coils in each branch being wound in opposite directions and the coils in one branch opposing the coils in the other branch, and means for opening the circuit of one parallel branch during the flow of pulses of one frequency and for closing said branch during the flow of pulses of another frequency whereby said printing mechanism is actuated by pulses of the first frequency only.

13. In a printing telegraph system, a circuit .rrangement adapted to transmit character selecting and printing current pulses of one polarity and also to transmit space repeating current pulses of the opposite polarity, receiving apparatus comprising a printing mechanism, and electro-magnet which, when energized, actuates said mechanism, a circuit arrangement for energizing said magnet including a plurality of coils in parallel branches, the successive coils in each branch being wound in opposite directions, a circuit controlling element actuated by pulses of the selecting and printing polarity only, a. second circuit controlling element actuated by pulses of the space repeating polarity only, means for opening the circuit of one parallel branch during the flow of printing pulses whereby said printing mechanism is actuated by printing pulses only, said second circuit controlling element having associated therewith means for short circuiting said opening means whereby said electro-magnet is deenergized during the flow of space repeating pulses.

14. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of one polarity, and also to transmit space repeating current pulses of the opposite polarity, receiving apparatus comprising a selecting mechanism, a printing mechanism, a circuit arrangement for actuating said printing mechanism including a magnet having a plurality of energizing coils in par allel branches, the coils in each branch being so wound that the magnetic flux developed by the coils of one branch are opposed by the coils of the other branch, a circuit controlling element actuated by pulses of the selecting and printing polarity only, a second circuit controlling element actuated by pulses of the space repeating polarity only, a capacity in one or said branches adapted to permit the flow of selecting pulses but to prevent the how of printing pulses in said branch whereby said printing mechanism is actuated by printing pulses only, and said selecting mechanism is actuated by the selecting pulses, said second circuit controlling element having associated therewith means for short circuiting said capacity.

15. In a printing telegraph system, apparatus adapted to transmit character selecting and printing current pulses of one polarity, and also to transmit space repeating current pulses of the opposite polarity, and receiving apparatus comprising a selecting mechanism, a printing mechanism, a circuit arrangement for actuating said printing mechanism including a. magnet having a plurality of energizing coils in parallel branches, the successive coils in each branch being wound in opposite directions and the coils in one branch opposing the coils in the other branch, a circuit controlling element actuated by pulses of the selecting and printing polarity only, a repeat relay actuated by pulses of the space repeating polarity only a capacity in one of said branches adapted to permit the flow of selecting pulses but to prevent the flow of printing pulses in said branch whereby said printing mechanism is actuated by printing pulses only, and said selecting mechanism is actuated by the selecting pulses, said repeat relay when energized being adapted to short circuit said capacity.

16. In a printing telegraph system, apparatus for transmitting character selecting and printing current pulses of the same polarity, receiv ing apparatus comprising printing and selecting mechanisms, driving motor for said mechanisms, an auxiliary starting circuit for said motor comprising a relay actuated by printing pulses, a supply circuit for said motor including a switch, said switch when closed shunting the auxiliary circuit to render it inoperative for controlling the operation of the motor.

17. In a printing telegraph system, a printing mechanism actuated by a press magnet, a driving motor for said mechanism, a supply circuit for said motor including a switch, means for opening said switch when said press magnet remains de-energized for a predetermined period and means for releasing said opening means.

18. In a printing telegraph system, a printing mechanism actuated by a press magnet, a driving motor for said mechanism, a supply circuit for said motor including a switch, means for opening said switch when said press magnet remains de-energized for a predetermined period and means actuated by the press magnet for releasing said opening means.

19. In a printing telegraph system, a printing mechanism actuated by a press magnet, a driving motor for said mechanism, a supply circuit for said motor including a switch, means for opening said switch when said press magnet remains de-energized for a predetermined period, said means comprising a longitudinally movable element which is moved in a direction to open said switch while the magnet remains de-energized, and means for retracting said element.

20. In a printing telegraph system, a printing mechanism actuated by a. press magnet having an armature, a driving motor for said mechanism'a supply circuit for said motor including a switch, means for opening said switch when said press magnet remains de-energized for a predetermined period, said means comprising a longitudinally movable element, a constantly rotating worm, a follower adapted so to move said element and engaging with said worm while the magnet remains de-energized, and means for retracting said element when the magnet is de-energized.

21. In a printing telegraph system, apparatus for transmitting character selecting and printing current pulses of the same polarity, receiving apparatus comprising printing and selecting mechanisms, a driving motor for said mechanisms, a supply circuit for said motor including a. switch, means for opening said switch when the printing mechanism remains inoperative for a predetermined period and for holding said switch open, an auxiliary starting circuit for said motor comprising a relay actuated by either selecting or printing pulses whereby the motor is started, means operable during the actuation of said printing mechanism for releasing said switch opening means, means' for closing said switch which, when closed, shunts the auxiliary circuit to render it inoperative for controlling the operation of the motor.

22. In a printing telegraph system, a lineoperated relay, 2. motor and a starting supply circuit therefor including said relay, 2. motor switch and a resistance adapted to generate sufficient heat to move said switch into running position whereby the supply circuit is altered.

23. In a. printing telegraph system, a. lineposition whereby the supply circuit is altered, said resistance being in series with said switch until the circuit is so altered.

24. Ina printing telegraph system, a line-operated relay, a motor and a starting supply circuit therefor including Said relay, a thermal switch and a resistance adapted to generate suflicient heat to move said switch into running position, said relay and resistance being in series with the source of supply and said switch while-the latter remains in starting position, said switch being directly connected to the source of supply when the switch is in running position.

25. In a printing telegraph system, a line-operated relay, a motor and a starting supply circuit therefor including said relay, a thermal switch and a resistance adapted to generate suflicient heat to mcve said switch into running position, said relay and resistance being in series with the source of supply and said switch while the latter remains in starting position, said switch being directly connected to the source of supply when the switch is in running position, a second resistance in series with the first resistance when the switch is in running position, said resistances being adapted to generate sufficientheat to maintain said switch in runnin'g'position,

26; lln a printing telegraph system, a lineoperated relay,-a motor and a starting supply circuit therefor including said relay, a thermal switch and a resistance adapted to generate sufflcient heat to move said switch into running position, said relay and resistance being in series with the source of supply and said switch while the latter remains in starting position, said switch being directly connected'to the source 01 Supply when the switch is in running position, a second resistance, substantially larger than the first resistance, in series therewith when the switch is in running position, said resistances and relay being then shunted across said switch and the motor, said resistances being adapted to generate suflicient heat, during normal operation of the line, to maintain said switch in running position.

27. In a printing telegraph system, a line-operated relay, a bell-sounding arrangement comprising a circuit including a bell and a thermal switch, a resistance in proximity to said switch and adapted to generate suiiicient heat to close said switch whereby the bell is sounded, the passage of current through said resistance being controlled by the operation of said relay.

28. In a printing telegraph system, a circuit arrangement adapted to transmit character selecting and printing current pulses of a single polarity and receiving apparatus comprising a selecting mechanism including a polarized magnet, and a printing mechanism, a circuit arrangement for actuating said printing mechanism in series with said polarized magnet and including a magnet having a plurality of energizing coils in parallel branches, a capacity in one of said branches adapted to permit the flow of selecting pulses but to block printing pulses in said branch whereby said printing mechanism is actuated by printing pulses only 1 and said selecting mechanism is actuated by. the 

